Constrained prosthetic knee with rotating bearing

Abstract

A constrained prosthetic knee having a modular hinge post and a rotating bearing. A cannulated hinge post is rotatably connected to the femoral component of the knee prosthesis so that a hinge post extension may be anteriorly positioned through the hinge post and into the tibial component of the knee prosthesis, after positioning of the femoral component in the femur and the tibial component in the tibia. The hinge post is preassembled to the femoral component so that such assembly is not required during the implantation procedure. A meniscal component forming the rotating bearing of the knee prosthesis is packaged together with the hinge post extension so that the appropriate hinge post extension is readily available. The meniscal component includes a mechanism for preventing lift off of the meniscal component from the tibial component, while allowing rotation of the meniscal component relative to the tibial component.

What is claimed is: 
     
       1. A prosthetic knee assembly, comprising:
 a femoral component body that includes a first internal side wall opposing a second internal side wall; 
 a hinge pin having a longitudinal hinge pin axis; 
 a hinge post positioned between the first internal side wall and the second internal side wall of the femoral component body, said hinge post rotatably connected to said femoral component body with said hinge pin passing through a hinge pin aperture in said hinge post so that rotation of said hinge post relative to said femoral component body is defined about the longitudinal hinge pin axis, said hinge post providing a hinge post extension aperture extending through the hinge post along a longitudinal hinge post axis that is non-intersecting with and transverse to said longitudinal hinge pin axis; and 
 a hinge post extension received in the hinge post extension aperture and removeably locked to the hinge post. 
 
     
     
       2. The prosthetic knee assembly of  claim 1 , further comprising a tibial component that includes an elongate aperture for receiving a distal section of said hinge post extension, wherein, when the femoral component body is attached to a femur and the tibial component is attached to a tibia opposite the femur, the distal section of the hinge post extension is insertable into the elongate aperture of the tibial component from an anterior surgical approach. 
     
     
       3. The prosthetic knee assembly of  claim 2 , wherein the hinge post extension being removeably locked to the hinge post includes a threaded connection between a proximal portion of the hinge post extension and an inner wall of the hinge post extension aperture. 
     
     
       4. The prosthetic knee assembly of  claim 3 , further comprising a bearing member that provides a first bearing side wall situated between the hinge post and the first internal side wall of the femoral component body and a second bearing side wall situated between the hinge post and the second internal side wall of the femoral component body. 
     
     
       5. The prosthetic knee assembly of  claim 1 , further comprising a plug member advanceable within said hinge post extension aperture to facilitate locking the hinge post extension to the hinge post, wherein said plug member is threadably advanceable along said longitudinal hinge post axis. 
     
     
       6. A prosthetic knee, comprising:
 a femoral component including a condylar bearing surface; 
 a hinge post rotatably connected to said femoral component about a rotational axis, said hinge post providing a hinge post extension aperture extending through the hinge post along a longitudinal hinge post axis that is non-intersecting with and transverse to said rotational axis; 
 a tibial component; 
 a hinge post extension receivable in the hinge post extension aperture for connection to the hinge post, said hinge post extension receivable in an elongate aperture of the tibial component; and 
 a meniscal component positionable between said femoral component and said tibial component so as to provide a cooperative bearing surface facing said condylar bearing surface of said femoral component, said meniscal component including a hinge post aperture in which said hinge post can be positioned, 
 wherein, when the femoral component is attached to a femur and the tibial component is attached to a tibia opposite the femur, said hinge post can be rotated about said rotational axis and said meniscal component can be inserted between the femoral component and the tibial component. 
 
     
     
       7. The prosthetic knee assembly of  claim 6 , wherein the hinge post extension includes a threaded proximal section for threadably engaging an inner wall of the hinge post extension aperture. 
     
     
       8. The prosthetic knee assembly of  claim 7 , wherein, when the femoral component is attached to a femur and the tibial component is attached to a tibia opposite the femur, a distal end of the hinge post extension can be passed through the hinge post extension aperture and into the elongate aperture of the tibial component from an anterior surgical approach. 
     
     
       9. The prosthetic knee of  claim 6 , wherein said tibial component includes a tibial tray with a protrusion protruding from the tibial tray, the protrusion cooperable with a cut-out in the meniscal component. 
     
     
       10. A prosthetic knee assembly, comprising:
 a femoral component body that includes a first internal side wall opposing a second internal side wall; 
 a hinge pin having a longitudinal hinge pin axis; 
 a hinge post positioned between the first internal side wall and the second internal side wall of the femoral component body, said hinge post rotatably connected to said femoral component body with said hinge pin fixed to said femoral component body and passing through a hinge pin aperture in said hinge post so that rotation of said hinge post relative to said femoral component body is defined about the longitudinal hinge pin axis, said hinge post including a longitudinal hinge post axis that is transverse to said longitudinal hinge pin axis and providing a hinge post extension aperture along said longitudinal hinge post axis, said hinge post extension aperture providing a first exterior opening in said hinge post and a second exterior opening in said hinge post, said first exterior opening and said second exterior opening spaced from one another along said longitudinal hinge post axis; and 
 a hinge post extension received in said hinge post extension aperture and removeably locked to the hinge post. 
 
     
     
       11. The prosthetic knee assembly of  claim 10 , wherein, when the femoral component body is attached to a femur, the hinge post extension can be unlocked from the hinge post and removed from the hinge post extension aperture from an anterior surgical approach. 
     
     
       12. The prosthetic knee assembly of  claim 10 , wherein the hinge post extension includes a distal end located outside the hinge post extension aperture and a threaded proximal portion located inside the hinge post extension aperture and threadably engaging an inner wall of the hinge post extension aperture. 
     
     
       13. The prosthetic knee assembly of  claim 10 , further comprising a tibial component that includes an elongate aperture for receiving the distal end of said hinge post extension. 
     
     
       14. The prosthetic knee of  claim 13 , further comprising a meniscal component positionable between said femoral component body and said tibial component, wherein said tibial component includes a tibial tray with a protrusion protruding from the tibial tray, the protrusion cooperable with a cut-out in the meniscal component. 
     
     
       15. A prosthetic knee, comprising:
 a femoral component including a condylar bearing surface; 
 a hinge post rotatably connected to said femoral component about a rotational axis, said hinge post providing a hinge post extension aperture extending through the hinge post along a longitudinal hinge post axis that is non-intersecting with and transverse to said rotational axis; 
 a tibial component; 
 a meniscal component positionable between said femoral component and said tibial component so as to provide a cooperative bearing surface facing said condylar bearing surface of said femoral component, said meniscal component including a hinge post aperture in which said hinge post can be positioned; and 
 a hinge post extension receivable in an elongate aperture of the tibial component for connection to the hinge post. 
 
     
     
       16. The prosthetic knee assembly of  claim 15 , wherein the hinge post extension includes a threaded proximal section. 
     
     
       17. The prosthetic knee assembly of  claim 16 , wherein the threaded proximal section is threadably engageable with an inner wall of the hinge post extension aperture. 
     
     
       18. The prosthetic knee assembly of  claim 17 , wherein, when the femoral component is attached to a femur and the tibial component is attached to a tibia opposite the femur, a distal end of the hinge post extension can be passed through the hinge post extension aperture and into the elongate aperture of the tibial component from an anterior surgical approach. 
     
     
       19. The prosthetic knee assembly of  claim 17 , wherein, when the femoral component is attached to a femur and the tibial component is attached to a tibia opposite the femur, the hinge post extension can be locked and unlocked from the hinge post from an anterior surgical approach. 
     
     
       20. The prosthetic knee assembly of  claim 15 , wherein the hinge post extension can be removeably locked to the hinge post so as to provide a distal shaft portion of the hinge post extension located outside the hinge post extension aperture and a threaded proximal section of the hinge post extension located inside the hinge post extension aperture and threadably engaging an inner wall of the hinge post extension aperture. 
     
     
       21. The prosthetic knee of  claim 15 , wherein said hinge post can be rotated about said rotational axis and said meniscal component can be inserted between the femoral component and the tibial component from an anterior surgical approach when the femoral component is attached to a femur and the tibial component is attached to a tibia opposite the femur. 
     
     
       22. The prosthetic knee of  claim 15 , wherein said tibial component includes a tibial tray with a protrusion protruding from the tibial tray, the protrusion cooperable with a cut-out in the meniscal component. 
     
     
       23. The prosthetic knee assembly of  claim 15 , further comprising a bearing member that provides a first bearing side wall situated between the hinge post and a first internal side wall of the femoral component and a second bearing side wall situated between the hinge post and a second internal side wall of the femoral component. 
     
     
       24. A prosthetic knee assembly, comprising:
 a femoral component body that includes a first internal side wall opposing a second internal side wall; 
 a hinge post positioned between the first internal side wall and the second internal side wall of the femoral component body, said hinge post rotatably connected to said femoral component body about a rotational axis, said hinge post including a longitudinal hinge post axis that is non-intersecting with and transverse to said rotational axis, said hinge post providing a hinge post extension aperture which provides a first exterior opening in said hinge post and a second exterior opening in said hinge post, said first exterior opening and said second exterior opening spaced from one another along said longitudinal hinge post axis; and 
 a hinge post extension received in the hinge post extension aperture and removeably locked to the hinge post. 
 
     
     
       25. The prosthetic knee assembly of  claim 24 , wherein the hinge post extension includes a distal end located outside the hinge post extension aperture and a threaded proximal portion located inside the hinge post extension aperture and threadably engaging an inner wall of the hinge post extension aperture. 
     
     
       26. The prosthetic knee assembly of  claim 25 , wherein the distal end of the hinge post extension is passable entirely through the hinge post extension aperture from the first exterior opening to the second exterior opening when receiving the hinge post extension in the hinge post extension aperture. 
     
     
       27. The prosthetic knee assembly of  claim 26 , wherein the threaded proximal portion of the hinge post extension is advanceable along the inner wall of the hinge post extension aperture in a direction from the first exterior opening toward the second exterior opening when removeably locking the hinge post extension to the hinge post. 
     
     
       28. The prosthetic knee assembly of  claim 24  further comprising a tibial component, with a distal section of said hinge post extension receivable in an elongate aperture of the tibial component. 
     
     
       29. The prosthetic knee assembly of  claim 28  further comprising a tibial bushing received in the elongate aperture of the tibial component, said tibial bushing including a first flange abutting a first transverse wall in the elongate aperture of the tibial component for retaining said tibial bushing in the elongate aperture of the tibial component, said hinge post extension including a second flange abutting a second transverse wall in tibial bushing for retaining said hinge post extension in the tibial bushing. 
     
     
       30. The prosthetic knee assembly of  claim 28  further comprising a meniscal component positionable between said femoral component body and said tibial component. 
     
     
       31. The prosthetic knee assembly of  claim 30 , wherein said tibial component includes a tibial tray with a protrusion protruding from the tibial tray, the protrusion cooperable with a cut-out in the meniscal component. 
     
     
       32. The prosthetic knee assembly of  claim 24 , wherein the hinge post extension is formed as a one-piece construction. 
     
     
       33. The prosthetic knee assembly of  claim 24  including a threaded connection locking the hinge post extension to the hinge post. 
     
     
       34. The prosthetic knee assembly of  claim 33 , wherein a threaded member is seated in the hinge post extension aperture to facilitate locking the hinge post extension to the hinge post. 
     
     
       35. The prosthetic knee assembly of  claim 24 , further comprising a bearing member that provides a first bearing side wall situated between the hinge post and the first internal side wall of the femoral component body and a second bearing side wall situated between the hinge post and the second internal side wall of the femoral component body. 
     
     
       36. The prosthetic knee assembly of  claim 35 , wherein the first bearing side wall includes a portion received in a side wall aperture in the first internal side wall of the femoral component body, and wherein the second bearing side wall includes a portion received in a side wall aperture in the second internal side wall of the femoral component body. 
     
     
       37. The prosthetic knee assembly of  claim 35 , wherein the first bearing side wall includes a side protrusion received in a side wall aperture in the first internal side wall of the femoral component body, and wherein the second bearing side wall includes a side protrusion received in a side wall aperture in the second internal side wall of the femoral component body. 
     
     
       38. The prosthetic knee assembly of  claim 35 , wherein said bearing member includes a curved back wall. 
     
     
       39. The prosthetic knee assembly of  claim 38 , wherein said curved back wall of the bearing member is cooperable in a convexo-concave fashion with a curvature in a back wall of the hinge post. 
     
     
       40. The prosthetic knee assembly of  claim 24 , wherein, when the femoral component body is attached to a femur, from an anterior surgical approach the hinge post extension can be unlocked from the hinge post and removed from the hinge post extension aperture to be replaced by a replacement hinge post extension. 
     
     
       41. A prosthetic knee, comprising:
 a femoral component that includes a condylar bearing surface and provides a first internal side wall opposing a second internal side wall; 
 a hinge post positioned between the first internal side wall and the second internal side wall of the femoral component, said hinge post rotatably connected to said femoral component about a rotational axis, said hinge post including a longitudinal hinge post axis that is non-intersecting with and transverse to said rotational axis, said hinge post providing a hinge post extension aperture which provides a first exterior opening in said hinge post and a second exterior opening in said hinge post, said first exterior opening and said second exterior opening spaced from one another along said longitudinal hinge post axis; 
 a tibial component; 
 a meniscal component positionable between said femoral component and said tibial component so as to provide a cooperative bearing surface facing the condylar bearing surface of said femoral component, said meniscal component including a hinge post aperture in which said hinge post can be rotatably received; and 
 a hinge post extension including a distal end and a threaded proximal portion, wherein said distal end can be passed entirely through the hinge post extension aperture from the first exterior opening to the second exterior opening so as to extend a distance from the hinge post for being received in an elongate aperture of the tibial component, and wherein said threaded proximal portion can be threadably advanced along the hinge post extension aperture in a direction from the first exterior opening toward the second exterior opening for removeably locking the hinge post extension to the hinge post. 
 
     
     
       42. The prosthetic knee of  claim 41 , wherein, when the femoral component is attached to a femur and the tibial component is attached to a tibia opposite the femur, (a) said meniscal component can be inserted between the femoral component and the tibial component from an anterior surgical approach; (b) said hinge post can be rotated about said rotational axis and received in the hinge post aperture of the meniscal component, wherein the first exterior opening in the hinge post is exposed for receiving the hinge post extension; (c) the distal end of the hinge post extension can be passed entirely through said hinge post extension aperture by entering the hinge post extension aperture through said first exterior opening and exiting the hinge post extension aperture through the second exterior opening; (d) the distal end of the hinge post extension can be received in the elongate aperture of the tibial component; and (e) the threaded proximal portion of the hinge post extension can be threadably advanced along the hinge post extension aperture in a direction from the first exterior opening toward the second exterior opening to removeably lock the hinge post extension to the hinge post.